Engraver for defining/generating edges or edge signals

ABSTRACT

This invention provides an engraving method and apparatus for engraving a plurality of cells which define a pattern defining at least one edge on a surface of a cylinder. The method and apparatus generate an edge signal corresponding to at least edge cell situated in a pattern defining at least one edge on the surface. The system and method may utilize a tabulator for tabulating a table of data corresponding to an image and a locator for locating the edge using the data. The system and method provide a signal generator which can cause the engraving location of an engraved area to be shifted to facilitate defining the at least one edge. Moreover, the signal generator may also cause the area to be reduced in order to change a predetermined characteristic of the area in order to better define the at least one edge. Thus, the invention facilitates adjusting a characteristic of at least one of the engraved areas in order to change a spacial relationship between the engraved area and another engraved are to provide, for example, a non-regular or non-periodic spacing of engraved areas. The invention provides a shaping data generator for generating shaping data to be used to modify the image data corresponding to an area to be engraved to redefine at least a portion of the data to provide an engraved area having a desired shape.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of Ser. No. 08/434,592 filed May 4, 1995,now U.S. Pat. No. 5,663,803, which is a continuation-in-part of Ser. No.08/125,938 filed Sep. 23, 1993, now U.S. Pat. No. 5,440,398, which is acontinuation-in-part of Ser. No. 08/038,679 filed Mar. 26, 1993, nowU.S. Pat. No. 5,438,422, which is a continuation-in-part of Ser. No.08/022,127 filed Feb. 25, 1993, now U.S. Pat. No. 5,424,845.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to engraving and, more particularly, to the artof engraving desired geometric patterns on a surface of a cylinder.

2. Description of Related Art

A helical gravure engraver creates periodic ink-receiving cavities,cells or areas on a printing cylinder by rotating the cylinder about itscylindrical axis while moving an engraving head in a direction parallelto the cylinder axis. Engraved areas are engraved on the surface of thecylinder by oscillating an engraving device, such as a diamond stylus,into engraving contact with the cylinder. A cell or cavity is engravedeach time the stylus is oscillated into contact with the printingcylinder. The resulting cavities are arranged along a continuous helicaltrack or in adjacent cylindrical tracks.

The stylus may be mounted on the engraving head as generally describedin Buechler, U.S. Pat. No. 4,450,486 and may be controlled as describedin related applications, Ser. Nos. 08/022,127, now U.S. Pat. No.5,424,845, and 08/038,679, now U.S. Pat. No. 5,438,422 filed Feb. 25,1993 and Mar. 26, 1993, respectively. As explained in Ser. Nos.08/022,127, now U.S. Pat. No. 5,424,845 and Ser. No. 08/038,679, nowU.S. Pat. No. 5,438,422 the stylus is oscillated at a frequency havingan odd number of half wavelengths during a full engraving rotation. Thiscauses a staggering of engraved areas engraved on successive rotationsof the cylinder. The engraving head is advanced an axial distance equalto one-half of a black cell width plus one-half of a connecting channelwidth, plus one separating wall width during each complete rotation ofthe printing cylinder. This causes a nesting of cavities which areengraved during successive rotations.

As also taught by Ser. Nos. 08/022,127 (now issued as U.S. Pat. No.5,424,845) and 08/038,679, (now issued as U.S. Pat. No. 5,438,422) theengraver engraves cavities having a size which corresponds to a greylevel to be printed by the printing cylinder. The cavity depth iscontrolled by a stylus driver acting in response to the combined levelsof a DC video signal, a white offset signal, and an AC signal. The DCgain and the AC gain may be controlled by a set-up circuit in accordancewith a series of set-up parameters.

While the above-described prior art system faithfully engraves cells ata regular frequency which will print a desired grey level, there is aproblem with edge definition. This is due to the fact that geometricalpatterns are represented by nested clusters of cells. This inventionprovides an apparatus and method for altering the relative positionbetween two or more engraved areas which, in turn, facilitates providingpatterns having, for example, improved edge or line definition.

SUMMARY OF THE INVENTION

An object of this invention is to provide a method and apparatus whichpermits spacing between engraved areas in a pattern to be changed ormanipulated. This, in turn, facilitates defining a pattern having anon-periodic or non-regular frequency arrangement of engraved cells.

In accordance with one method of the invention, a cylinder is engravedwhile being rotated about its cylindrical axis. An engraving device isoscillated into engraving contact with the surface of the cylinder whilebeing axially advanced in synchronism with the rotation and theoscillation. The frequency of the oscillation is such that cavities insuccessive helical turns are circumferentially shifted one-half of anoscillating wavelength. Axial advancement of the engraving deviceproceeds at a speed such that cavities engraved during any helical turnare nested with cavities in columns engraved during adjacent turns.Shifting and compression, for example, of an engraved area is producedby generating shaping data and applying this data to combined datacorresponding to at least a portion of an image.

The apparatus of the invention comprises a driver for driving theengraving device into engraving contact with a cylinder, video signalmeans connected to the driver for causing the engraving device toperform an engraving action corresponding to an image to be reproduced,oscillation signal means connected to the driver for causing theengraving action to proceed by engraving a series of cavities at anon-regular or non-periodic frequency, and cavity-shaping meansoperating in timed relation for adjusting the placement of an edge of alead cavity in a series of cavities.

It is therefore an object of the invention to improve, among otherthings, the edge definition of a pattern engraved upon a cylinder.

A further object of the invention is to provide a method for engravingan image having at least one edge and comprising the step of engravingan area having a redetermined dimension to facilitate defining the atleast one edge.

Still further object of the invention is the provision of a method forengraving an image having at least one line on a cylinder in an engravercomprising the steps of generating at least one signal corresponding toa plurality of engraved areas which make up at least a portion of saidimage and processing the at least one signal in order to alter adimension of at least one of said plurality of engraved areas.

Yet another embodiment of the invention is a method for modifying a cellcharacteristic of a cell to be engraved in a surface of a workpiececomprising the steps of identifying said cell to be modified andmodifying an engraving signal corresponding to the cell in order tochange at least one engraving characteristic of the cell.

Still yet another object of the invention is the provision of a methodfor engraving a plurality of engraved areas corresponding to an imagecomprising the steps of modifying a characteristic of at least one ofthe plurality of engraved areas to provide at least one modifiedengraved area, generating a signal in response to said at least onemodified engraved area and energizing an engraving device to engrave apattern in response to the signal.

A further object of the invention is to provide a method of engravingcomprising the steps of rotatably mounting a cylinder in an engraver,situating an engraving device in operative relationship with thecylinder, modifying a characteristic of at least one of the plurality ofengraved areas to provide at least one modified engraved area,generating a second signal in response to the first signal and the atleast one modified engraved area, and energizing an engraving device toengrave a pattern in response to the second signal.

Another object of the invention is to provide an engraver for engravinga pattern having at least one edge, comprising a bed, a headstock and atailstock for rotatably supporting a cylinder on the bed, an engravingdevice mounted on said bed for engraving a surface of the cylinder, acontroller for controlling operation of the engraver and coupled to theengraving device, and a signal generator located in the controller forreceiving image data corresponding to an engraved area having apredetermined characteristic, for processing the image data in order tochange the predetermined characteristic to facilitate defining the atleast one edge, and for generating an engrave signal in response theretofor energizing the engraving device.

Another object is to provide a engraver for modifying or altering acharacteristic, dimension or location of data associated with an area tobe engraved to facilitate defining a pattern having a desired feature,such as sharp definition.

Other objects and advantages of the invention will be apparent from thefollowing written description, the attached drawing and the appendedclaims.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

FIG. 1 is a general schematic view of an engraver 10 according to thisinvention;

FIG. 2 is a partly broken away view of a pattern comprising a pluralityof engraving areas and also illustrating two engraving areas which havebeen shifted and compressed to facilitate defining an edge or line 36;

FIG. 3 is another fragmentary view of cylinder 14 showing anotherpattern of a plurality of engraved areas and also showing a verticaltrench or elongated cavity which defines an edge 36a;

FIG. 4 is a view showing a steady state signal, cavity shaping signaland video drive signal;

FIG. 5 is a view of a combined output signal;

FIG. 6 is a general flow chart of a method in controller 17 according toone embodiment of this invention;

FIG. 7 is a flow chart of a set-up routine situated in controller 17;

FIG. 8 is a flow chart of a load image data routine situated incontroller 17;

FIG. 9 is a flow chart of a scan routine performed by controller 17;

FIG. 10 is a flow chart of a gain method executed by controller 17;

FIG. 11 is a flow chart showing a DC gain routine;

FIG. 12A is another flow chart illustrating a combined routine andmethod for combining video data with steady state data;

FIG. 12B illustrates a table situated in controller 17 comprising aplurality of data values which define a period for a sinusoidal waveform;

FIGS. 13A-13B are flow charts which illustrate a shift method or routineperformed by controller 17;

FIG. 13C illustrates a plurality of signals plotted from data in a shifttable which is situated in controller 17 and which comprises a pluralityof shaping signals suitable for shaping combined signal generated by theroutine shown in FIG. 12A;

FIG. 14 illustrates a filter routine in accordance with one embodimentof the invention;

FIG. 15 is a flow chart of an output gain/scale and offset routine;

FIG. 16 is a flow chart of an engraving routine;

FIG. 17 is a flow chart which defines or describes an image data routineused herein;

FIG. 18 illustrates a second embodiment of the invention forfacilitating defining a vertical edge, such as edge 100 in FIG. 3;

FIG. 19 a flow chart of a set-up routine situated in controller 17;

FIG. 20 is a flow chart of a load image data routine situated incontroller 17;

FIG. 21 is a flow charge illustrating a vertical edge scan routine forlocating vertical edges in image data;

FIGS. 22A-22B are flow charts which illustrate a horizontal edge methodor routine situated in controller 17 for locating horizontal edges inthe image to be engraved;

FIG. 23 is a flow chart of a gain method executed by controller 17;

FIG. 24 is a flow chart showing a DC gain routine;

FIG. 25 is another flow chart illustrating a combined routine and methodfor combining video data with steady state data;

FIG. 26 is a flow chart illustrating a disable routine for disablingand/or replacing a portion of combined image data as desired;

FIGS. 27A-27D are flow charts illustrating a method or routine utilizedby controller 17 relative to the disable routine in FIG. 26;

FIG. 28 illustrates a filter routine in accordance with one embodimentof the invention;

FIG. 29 is an output gain/scale and offset routine;

FIG. 30 is an engraving routine;

FIG. 31 is a flow chart which defines or describes an image data routineused herein; and

FIG. 32 is an illustration of a waveform which was combined, and/ormodified in accordance with the embodiment described relative to FIGS.18-31.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 is a general perspective view of a preferred embodiment of anengraver, designated generally as engraver 10. In the embodiment beingdescribed, the engraver 10 is a gravure engraver, but the invention maybe suitable for use in other engravers, such as laser engraving. Theengraver 10 may have a surrounding, slidable safety cabinet structurewhich is not shown for ease of illustration. Engraver 10 comprises abase 12 having a headstock 16 and a tailstock 18 slidably mounted intrack 20 such that the headstock 16 and tailstock 18 can move towardsand away from each other. In this regard, engraver 10 comprises aplurality of linear actuators or first drive motor means or first drivemotor 46 and a second drive motor means or second drive motor 48 whichare capable of driving the headstock 16 and tailstock 18, respectively,towards and away from each other. For example, the drive motors maycause the headstock 16 and tailstock 18 to be actuated to a fullyretracted position (not shown) or to a cylinder support position shownin FIG. 1.

The drive motors may be selectively energized to cause the headstock 16and tailstock 18 to be actuated either independently or simultaneously.Although not shown, a single drive motor may be used with a singleleadscrew (not shown) having reverse threads on which either end causesthe headstock 16 and tailstock 18 to move simultaneously towards andaway from each other as the leadscrew is driven. Driving both headstock16 and tailstock 18 permits cylinders 14 of varying lengths to be loadedby an overhead crane, for example, whose path is perpendicular to theaxis of rotation of the cylinder 14. Although not shown, it should beappreciated that a stationary headstock 16 or tailstock 18 may be usedwith a driven tailstock 16 or headstock 18, respectively.

The headstock 16 and tailstock 18 comprise a first support cone or shaft16a and a second support cone or shaft 18a, respectively. The supportshaft 16a and 18a each comprises a conically shaped end which issuitable for engaging and rotatably supporting cylinder 14 at anengraving station 15 of engraver 10. In this regard, the cylinder 14comprises a first end 14a and a second end 14b, each having a receivingopening for receiving end 16b and 18b, respectively. The receivingopenings in ends 14a and 14b are conically shaped in cross-section so asto matingly receive ends 16b and 18b of cones 16 and 18.

Although not shown, if a shafted cylinder (not shown) was to beengraved, then headstock 16 and tailstock 18 would each include agripping device or chuck (not shown) for receiving the shafts and alsofor rotatably supporting the cylinder 14 at the engraving station 15.

The engraver 10 also comprises an engraving head 22 having an engravingdevice, such as a cutting tool or stylus 23 for engraving a surface 13of cylinder 14. In the embodiment being described, the engraving device23 preferably has a diamond stylus; however, it should be appreciatedthat the invention may be used with other types of engraving devices,including, for example, laser engraving devices.

The engraving head 22 is slidably mounted on a carriage 24 such that athird drive means or third drive motor 21 can drive the engraving head22 towards and away from the surface 13 of cylinder 14 in a directionwhich is generally radial with respect to the rotational axis ofcylinder 14. The carriage 24 is also slidably mounted on base 12 suchthat it traverses the entire surface 13 of cylinder 14 in the directionof double arrow 26 in FIG. 1, which is generally parallel to the axis ofthe cylinder 14. The engraver 10 also comprises a lead screw (not shown)and drive motors (not shown) for causing the carriage 24 to move in thedirection of double arrow 26. The engraving head 22, carriage 24 andtransverse movement thereof is similar to that shown in Ser. Nos.08/038,679; 08/022,127; and 08/023,060, which are assigned to the sameassignee as the present invention and which are incorporated herein byreference and made a part hereof.

The engraver 10 also comprises drive means or a drive motor 28 forrotatably driving the support member 16a, cylinder 14, and supportmember 18a. The drive motor 28 is also operatively coupled to thecontroller 17, as shown.

The engraver 10 comprises a programmable controller or processor 17which controls the operation of the engraver 10 and which also controlsdrive motors 21, 28, 46 and 48 mentioned earlier herein.

Although not shown, the engraver 10 may further comprise a support orsupport means for supporting the cylinder 14 between headstock 16 andtailstock 18, for example, during loading and unloading.

Controller 17 is also coupled to engraving head and is capable ofenergizing engraving head 22 to engraver at least one controlled-deptharea or cell as carriage 24 traverses surface 13 of cylinder 14 in amanner described later herein.

In accordance with the present invention, an improved engraving methodand system is provided for manipulating or modifying input data so as tolocate one or more engraved areas 30 (FIG. 2) at a predeterminedlocation 32 in a pattern 34. This invention is particularly useful indefining, for example, a horizontal line or edge 36 (FIG. 2) or verticalline or edge 36a (FIG. 3). For ease of illustration, the horizontal edge36a, as viewed in FIG. 2, is assumed to be generally parallel with anaxis of rotation of cylinder 14.

As illustrated in FIG. 2, improved edge definition may be obtained for apattern of engraved areas 38a, 38b, 40a and 40b in surface 13 ofcylinder 14 (FIG. 1). It should be appreciated that FIG. 2 illustratesonly a portion of surface 13 of cylinder 14 which is rotating about itscylindrical axis to produce a surface motion or rotation indicated byarrow A in FIG. 2. As illustrated in FIG. 2, the edge or line 36 isdefined by engraved areas 38a and 40a. In general, the engraved areas38a, 38b, 40a and 40b are arranged in a series of nested columns, eachhaving a lead cavity 38a or 40a positioned with its leading edge inalignment with the line or edge 36. It will be appreciated that adjacentcolumns of cavities may be produced by oscillating the engraving stylus23 into engraving contact with cylinder 14 during successive helical orcylindrical passes thereof.

The engraver 10 may produce the engraved pattern 34 by commencing toengrave a series of engraved areas along a column 29 each time the edge36 transits past the engraving stylus 23 on engraving head 22 andcontinuing until the beginning of another column, such as column 31 inFIG. 2.

Sharp, edge or line pattern definition in a pattern is produced inaccordance with this invention by adjusting, modifying or engraving anengraved area, such as area 30 in FIG. 2, to a predetermined dimensionas may be required by the pattern being engraved. For example, sharpedge definition is produced in accordance with this invention bycompressing and shifting the lead cavities in alternate cavity columns.Thus, lead cavities 38a are engraved in normal fashion, while leadcavities 40a are compressed and shifted. For comparison purposes, FIG. 2illustrates in phantom lines, prior art cavities 41 corresponding tocompressed and shifted areas 40a of the present invention. It will beseen that the center of each lead area 40a is shifted in the engravingdirection (i.e., opposite the direction of the arrow A) a distance S.Note that lead cavities 40a are compressed so as to have a length L1 inthe engraving direction, while the corresponding length for anon-compressed and shifted cavity is L2.

In general, features of this invention are achieved by analyzing inputdata associated with one or more of the engraved areas 38a, 38b, 40a,40b, which make up the pattern 34. The data is analyzed to identify oneor more engraved areas or cells which will be modified and also toanalyze the pattern 34 prior to engraving such that the dimension orlocation of one or more of the engraved areas in the pattern 34 may bemodified or adjusted.

If it is desired to modify a characteristic, dimension and/or locationof one or more of the engraved areas which make up pattern 34, then thedata associated with the area may be modified or adjusted as describedlater herein. Controller 17 then energizes engraving head 22 to engravethe engraved area in accordance with the modified data so as to causethe engraved area to be dimensioned or located as desired in the pattern34.

FIG. 4 illustrates waveforms for control signals which may be used forengraving a pattern of cavities of the type illustrated in FIG. 2.Preferably, three signals are provided. These signals are combined tocontrol or drive the engraving device of engraving head 22 such that itengraves the cells 38a, 38b, 40a and 40b in a manner which will definethe desired pattern 34. The three signals are a steady state oscillationsignal 42, a video drive signal 44 and a cavity shaping signal 46. Itshould be appreciated that the video drive signal 44 comprises the videodata information associated with the image (not shown) to be engraved onsurface 13 of cylinder 14. The steady state oscillation signal 42 causesradial oscillation of the engraving stylus 23 at a frequency whichproduces a nesting of engraved areas engraved during successiverotations of cylinder 14.

Video drive signal 44 is added to steady state oscillation signal 42 togenerate a first drive signal which controls the movement of theengraving device 23 at all times except during engraving of the engravedareas 40a. Video drive signal 42 has a step 42a which connects anon-engraved portion 42b and an engraved portion 42c. When the portion42b is added to steady state oscillation signal 42, the engraving device23 oscillates out of contact with surface 13 of cylinder 14. Engravingis performed when video drive signal 44 transitions to portion 44c.

FIG. 3 illustrates the response of the engraving device 23 to a combinedsignal 48 of FIG. 2. A profile line 48 represents the motion of a tip ofthe engraving device 23 relative to surface 13 of cylinder 14. When theportion 44b of video drive signal 44 is added to steady stateoscillation signal 42, the engraving stylus follows profile portion 48awhere it is out of contact with surface 13 of cylinder 14. When thevideo drive signal 44 is at portion 44c and is combined with steadystate oscillation 42, profile line 46 transitions to the line portion46b where the stylus periodically engraves engraved areas 38a, 38b, and40b. When cylinder 14 is being engraved for printing of copy whichcomprises the line or edge 36 (FIG. 2), then video drive signal 44shifts from level 44b to level 44c for each white/black transition andfrom level 44c to level 44b for each black/white transition. In the casewhere cylinder 14 which is being engraved for printing of multiple tonesor grey levels, video drive signal 44 will be stepped between a seriesof different voltages.

When it is desired to engrave areas 40a, then engraver controller 17temporarily switches off signal 42 and creates a second stylus drivesignal by combining shaping signal 46 to video drive signal 44. Theshaping signal 46 has a profile which, when added to portion 44c ofsignal 44, causes the engraving device 34 to follow the portion 48c ofprofile 48. As illustrated in FIG. 4, shaping signal 46 has a dip orminimum point 46a which is delayed by a time T from a corresponding dipor minimum point 42a in signal 42. This time T is directly proportionalto the distance S of FIG. 2 and represents the distance which the area,such as phantom cell 41 in FIG. 2, has been repositioned or shifted.

Notice in FIG. 5 that the length L1 represents the length which shapingsignal 46 caused cell 40a to be compressed from an original length, suchas length L2. It should be appreciated, however, that shaping signal 46may comprise any suitable or desired form as may be required by thedimension, shape or area of the engraved area, such as engraved area40a, to be engraved in pattern 34 (FIG. 2).

The profile of shaping signal 46 may be determined by simply drawing thedesired engraving stylus profile line portion 48c, adding an offset forthe video drive signal 44 and making a conversion to the time domain. Itwill be appreciated that there may be considerable variation in thesize, arrangement and/or spacing of engraved areas 38a, 38b, 40a, and40b in that this may effect the modification, arrangement, shiftingand/or compression of one or more of the engraved areas. Accordingly, itis desirable to establish a plurality of shaping signals 46 from whichto choose and to store digitized representations of these profiles in anappropriate non-volatile memory. This may be accomplished in accordancewith the method illustrated in FIGS. 6-17.

FIGS. 6-17 illustrate flow charts for modifying image data associatedwith one or more of the engraved areas which make up pattern 34 (FIG. 1)in order to alter, change or eliminate a characteristic dimension orlocation of the area to, for example, define edge 36 (FIG. 2) and edge36a (FIG. 3).

Referring now to FIGS. 6-17, a first embodiment is shown comprising amethod or routine for identifying and processing data for an engravedarea in order to shift the location if that area from a first location adistance L1 to another location where the pattern 34 is engraved.

FIG. 6 illustrates a method or routine for modifying, shifting and/orrelocating at least one of the engraved areas, such as engraved area 40a(FIG. 2). As illustrated in FIG. 6, the routine starts at block 199 bysetting up a plurality of buffers D1, D2, D3, F1 and OP in memory ofcontroller 17. These buffers are used by the routines, procedures andmethods described herein and are set up in accordance with the proceduredescribed below relative to FIG. 7.

At block 200, image data associated with an image (not shown) to beengraved is loaded into the data buffers D1, D2, D3 in controller 17 inaccordance with the procedure described below relative to FIG. 8. In theembodiment being described, each engraved area, cell of cavity isrepresented by four data samples of one byte. The one byte samplesrepresent density values for the engraved area and range from zero to255, with 255 being the darkest tone or density. Each data buffer D1, D2and D3 is loaded with a column of data for a column, such as column 31in FIG. 2, of areas to be engraved. For example, data buffer D2 isloaded with image data corresponding to column 31 (FIG. 2) while databuffers D1 and D3 are loaded with image data corresponding to columns 29and 33, respectively.

At block 202, controller 17 comprises a scanner or means for performinga scan routine for scanning data buffer D2 in order to determine thelocation of a line or edge in the image to e engraved, such as edge 36(FIG. 2), by examining black/white and white/black transitions. Thescanner or scanning means or routine is shown in FIG. 9 which isdescribed in detail below.

The image data is input data buffers D1, D2 and D3 in controller 17 at 4samples per engraved area. It is desirable to enhance the engravingperformed by the engraving head 22 by generating an energizing or outputsignal to engraving head 22 which represents more samples per engravedarea. In this embodiment, it has been found that 32 samples of outputdata. This feature is achieved by reproducing the input data samples aplurality of times which is set at eight. This is achieved by theprocedure shown in FIG. 10 and described later herein.

At block 204, the image data located in data buffer D2 is copied into anoutput buffer OP in controller 17. The value represented by the 32 bitsranges from minus 2 to plus 2 billion. The submethod or subrouteassociated with blocks 200 and 202 is described below relative to FIGS.8 and 9, respectively, described later herein.

The method continues at block 206 where a DC scaling or gain routine isperformed in order to scale the video signal, such as video signal 44(FIG. 4), which is generated by controller 17. This procedure forscaling is shown in FIG. 11 which is described later herein.

At block 208 (FIG. 12) an AC signal, such as steady state signal 42 inFIG. 4, which was generated by controller 17 is combined or summed withDC data corresponding to video signal 44 in accordance with the methodor routine shown in FIG. 12 and described in detail below. Next, a shiftroutine described later herein relative to FIG. 13A and 13B, modifiesthe combined or summed data in order to change a dimension,characteristic or location of an area which is engraved in response tothat combined data.

Next, controller 17 comprises a filter or filtering means comprising afilter method (block 212) for combining and modifying the combined datain order to modify the signal to compensate for the responsecharacteristics of engraving head 22.

The method proceeds to block 214 where an output gain and offset meansor routine situated in controller 17 is performed in accordance with theroutine shown relative to FIG. 15 and described later herein. It shouldbe appreciated that after the filter method (block 212) is performed, itmay be desirable to scale the data to a desired oscillation range forhead 22. This procedure also applies an offset to the combined data tocompensate for a shoe position or other engraving head 22 offsets.

At block 216, a controller 17 comprises means for performing an outputprocedure. This procedure reads output data from buffer OP todigital-to-analog converter 19 (FIG. 1) which generates an engravingsignal which is, in turn, amplified by amplifier 21 and then used toenergize engraving head 22.

The numeric values for the output data stored in output buffer OPrepresent voltage levels which are passed to engraved head 22 using D/Aconverter 19. It should be appreciated that the combined data in bufferOP corresponds to two columns of data for two columns of areas, such ascolumns 29 and 31 in FIG. 24, any one or both of which may compriseimage data which was modified. Alternatively, it should be appreciatedthat, although the image data was processed, some or all of that datamay remain unmodified so that no shifting of an area to be engravedtakes place.

At block 216, controller 17, in turn, energizes engraving head 22(FIG. 1) to engrave the shifted engraved area.

Thereafter, the method proceeds to decision block 220 where control 17determines if all original input data corresponding to the image to beengraved has been processed. If it has, then the main routine iscomplete. If it has not, controller 17 obtains new image data inaccordance with an image data routine or means (block 222) situated incontroller 17 and then loops back to block 202 as shown. In general, thefunction of the image data routine is to obtain the next column of datato be processed by the method.

Having described the overall method or procedure employed, the varioussubmethods or subroutines referred to above will now be described inmore detail.

The setup buffer procedure will now be described relative to FIG. 7. Theprocedure starts at block 221 where a number of engraved areas, such asa number of cells, is entered into controller 17. In this embodiment,the number of cells for two revolutions of cylinder 14 are input. Atblock 223, the data buffers D1, D2, D3 and F1 in memory of controller 17are set to a predetermined length which in this embodiment is four timesthe number of cells input at block 221. This enables controller 17 toprocess four samples of data for each engraved area or cell.

At block 225, the output buffer or length is set to 32 times the numberof engraved ares or cells. This facilitates enabling controller 17 tooutput 32 samples per engraved area or cell output buffer OP to O/Aconverter 19 (FIG. 1). After the buffers D1, D2, D3, F1 and OP are setup in controller 17, the method returns to block 200 (FIG. 8).

As illustrated in FIG. 8, controller 17 performs the load image dataroutine by setting buffers D1, D2, D3 equal to zero (block 224 in FIG.8). Next, a first column of image data is loaded into the middle bufferD2 at block 226, and then a second column of image data is loaded intobuffer D3 (block 228). The flag buffer F1 is cleared at block 230 andthen the procedure returns to block 202 in FIG. 6, whereupon thecontroller 17 performs the scan method illustrated in FIG. 9.

The scan method begins at block 234 where a size of data buffer D2 isset equal to a predetermined length which, in the embodiment beingdescribed, was determined at block 223 in FIG. 7. The method proceeds atblock 234 (FIG. 9) where an INDEXL variable is set equal to zero and theflag buffer F1 is cleared. At block 236, image data stored in databuffer locations D2 INDEXL! and D2 INDEXL+1! are read by controller 17.

At decision block 238, it is determined if the value stored at positionD2 INDEXL! equals a predetermined threshold (e.g., 255) and if the valuestored at position D2 INDEXL+1! is equal to a second threshold (e.g.,zero). The first and second thresholds correspond to a black and whiteportion, respectively, of the image. If it is, then the method sets aflag in flag buffer F1 at FI INDEXL+1!. This flag identifies ablack-to-white transition. After block 240, the method proceeds to block246 as shown.

If the decision at decision block 238 is no, then the method proceeds todecision block 242 where it is determined if the value stored atposition D2 INDEXL! equals a predetermined threshold (e.g., 0) equalsand if the value stored at position D2 INDEXL+1! is equal to a secondthreshold (e.g., 255). The first and second thresholds correspond to awhite-to-black transition. If the decision at block 242 is yes, then theflag in flag buffer F1 at FI INDEXL! is set. If the decision at decisionblock 242 is negative, then the method increments INDEXL at block 246and then proceeds to decision block 248 where it is determined if theINDEXL is equal to the D2 buffer length. If the INDEXL is not equal tothe D2 buffer length, then the method loops back to block 236 as shown;otherwise it proceeds to block 204 (FIG. 6).

Thus, it should be appreciated that the scan routine illustrated in FIG.9 identifies and locates the white-to-black and black-to-whitetransitions. Once these transitions are located, the data in data bufferD2 is copied by controller 17 into output buffer OP in accordance withthe routine shown in FIG. 10.

Referring now to FIG. 10, controller 17 processes the image data inbuffer D2. Initially, an INDEXA is set equal to zero and INDEXB is alsoset equal to zero at block 308. At block 310, COUNTA is set equal tozero.

The method proceeds to block 312 where an image data value in the memoryof controller 17 located at D2 INDEXA! is read by controller 17. Thatdata value is loaded into output buffer OP in controller 17 at the OPINDEXB! location (block 314). At block 316, INDEXB is then incrementedby one, and COUNTA is incremented by one.

At decision block 318, it is determined if the COUNTA is equal to apredetermined count, such as eight samples, and if it is not, the methodloops back to block 314 as shown. If it is equal to eight, then themethod proceeds to block 320 where INDEXA is incremented by one. Atdecision block 322, it is determined if the INDEXA is equal to a lengthof the D2 buffer. If it is not, then the routine loops back to block 310where another data value at the D2 INDEXA! location is read andprocessed. If the decision at decision block 322 is yes, then the methodis complete.

Upon completion of the copy routine illustrated in FIG. 10, thecontroller 17 proceeds to perform the DC gain routine (block 206 in FIG.6) which is illustrated in FIG. 11. The gain routine proceeds byinputting a DC gain value to controller 17, and setting an INDEXCvariable equal to zero (block 326). The DC gain value is scanned into orotherwise input into controller 17. The routine proceeds to block 328where a VALUEA from the data buffer OP INDEXC! is read (block 328). Atblock 330, a new VALUEB is set equal to VALUEA times a DC gain or scalefactor which is generated by controller 17. The new VALUEB is thenloaded into the output buffer OP at location OP INDEXC! (block 332), andthe INDEXC is incremented by one (block 334).

The method proceeds to decision block 336 where it is determined if theINDEXC is equal to the OP buffer length and, if it is not, the methodloops back to block 328 as shown. Otherwise, the method is complete.

After the DC gain/scale method is performed (block 206 in FIG. 6),controller 17 proceeds to perform the combine routine (block 208 in FIG.6) which is illustrated and described relative to FIG. 12A. The purposeof the combine method is to apply an AC steady state signal to the imagedata which was processed as described earlier herein. In this regard,the method begins by initializing a sine wave table 57 size in memory ofcontroller 17 at 32 samples per cycle or per engraved area (block 340).At block 342, an INDEXD is set equal to zero. Thereafter, a sine wavedata value 57a VALUEB is read by controller 17 (block 344 in FIG. 12B).The sine wave table 57 in controller 17 comprises a sine waveform onecycle in length with 32 samples in the embodiment being described. Asuitable sine wave table is illustrated in FIG. 12A.

The controller 17 utilizes this sine wave table 57 to facilitatesuperimposing the DC gain data corresponding to signal 44 (FIG. 4)generated by the DC gain routine onto a sine wave, such as the steadystate signal 42a, to provide a combined engraving signal (like signal 48in FIG. 5). At block 346 (FIG. 12A), a VALUEC is set equal to the datavalue in output buffer OP at location OP INDEXD!. At block 348, VALUEDis set equal to VALUEB from the sine wave table (block 344) plus thedata VALUEC which was read at block 346.

The VALUED is loaded into the output buffer at location OP INDEXD! atblock 350 (FIG. 12A) and then the INDEXD is incremented by one (block352). At decision block 354, it is determined if the INDEXD is equal tothe length of the output buffer OP. If it is not, the method loops backto block 344 as shown. If it is equal, then the method is complete andreturns to block 210 in FIG. 6.

It should be appreciated that the four samples of image data per engravearea may be represented by signal 44 (FIG. 4). This image data has beencombined with the sine wave steady state signal, such as represented bysignal 42 in FIG. 4, to provide combined data. This combined data may berepresented by signal 48 in FIG. 5, which comprises 32 samples perengraved area.

Once the combine routine is performed by controller 17, the methodproceeds to modify the combined data generated so that an engraved areacorresponding to that combined will be shifted, for example, thedistance S in FIG. 2 using the shift routine (block 210 in FIG. 6)illustrated relative to FIGS. 13A and 13B. As illustrated in FIG. 13A,an INDEXE is set equal to zero (block 358). A VALUEE is set to the valuelocated at flag buffer F1 INDEXE! (block 360). It is then determined ifa VALUEE is equal to zero. If it is not, the method proceeds to decisionblock 364 where it is determined if the VALUEE represents ablack-to-white transition (block 364). If it does not, then the processproceeds to determine (block 370) if the VALUEE represents awhite-to-black transition. If the decision at decision block 362 is yesor the decision at block 370 is no, then the process proceeds toincrement the INDEXE by one. If the decision at decision blocks 364 and370 are yes, then the method proceeds (block 368) to modify the outputbuffer OP data to adjust a position of the area which will be engravedin accordance with the shift routine shown in FIG. 13B.

Thereafter, it proceeds to increment INDEXE by one (block 366). Atdecision block 372, it is determined if the INDEXE is equal to thelength of the F1 buffer. If it does, then the transition method iscomplete. If it is not, the method loops back to block 360 as shown.

Thus, it should be understood that the method in FIG. 13A facilitateslocating edges defined as black-to-white or white-to-black transitions.Once these transitions are known the method may proceed to modify oralter the combined image data to cause the area to be engraved inresponse to that data to be shifted.

Referring now to FIG. 13B, the shift cell routine is illustrated. Thismethod proceeds by setting an INDEXF equal to INDEXE times 8. It shouldbe appreciated the flag value at F1 INDEXE! corresponds to ablack-to-white or white-to-black transition. The combined datacorresponding to this transition is located in output buffer OP atmemory location OP INDEXF!.

A phase variable, PHASEA, is computed as the INDEXF modulus 4 (block378). In this embodiment, the Phase A variable represents the positionof the transition relative to, or along, the sine wave generated atblock 344 (FIG. 12A). This, in turn, facilitates determining where anengraved area, such as in cell 41 (FIG. 2), the transition is located.In this embodiment, there are four phases or samples per sine wavecycle. For each phase, there is a look-up or shift table situated incontroller 17 which comprises a plurality of data values. As illustratedin FIG. 13C, waveform plots 381, 383, 385 and 387 are shown. Thesewaveforms 381, 383, 385 and 387 correspond to the data values in eachshift table. A representative shift table 381 of shift data waveforms isillustrated in FIG. 13C. The shift waveform from the waveform table islocated in controller 17 (block 380). The shift waveform correspondingto the phase value is loaded into a buffer S1 in controller 17. A COUNTBis set equal to zero (block 382), and a VALUEJ is set equal to the valuelocated at a buffer S1 in controller 17 at position buffer S1 COUNTB!(block 384). At block 386, the VALUEJ is stored in output buffer OP atthe OP INDEXF! location. At block 388, COUNTB is incremented by one, andINDEXF variable is incremented by one. It is then determined if theCOUNTB is equal to a length of the S1 buffer at decision block 390. Ifit is, then the method is complete and returns to block 212 in FIG. 6.If it is not, the method loops back to decision block 384 as shown.

After the image data has been processed and any dimension orcharacteristic of an area to be engraved is modified, adjusted orshifted to achieve a desired engrave pattern (for example, to define anedge or line in an image to be printed by the cylinder) the methodproceeds to a filter routine as illustrated in FIG. 14. In this regard,controller 17 comprises a filter or filtering means for filteringcombined data after it has been processed as described above.

The filter routine facilitates modifying the frequency content of theprocessed data so that the engaging head 22 and engraving device 23respond to engrave the desired pattern. This is necessary because thenature frequency response of engraving head 22 may not produce desiredresults when excited with a non-filtered signal. The filter routine(FIG. 14) begins at block 396 where an INDEXG is set equal to zero. Themethod proceeds to block 398 where a VALUEF is set equal to in OPINDEXG!. The data VALUE F represents a single data value from outputbuffer OP (INDEXG). Thus, each data value in output buffer OP isprocessed. This data VALUEF is then convolved using the filter andprocedure described herein.

In the embodiment being described, one suitable filter is an infiniteimpulse response (IIR) digital filter situated in controller 17, but itshould be appreciated that the invention may be practiced withnon-digital filters. The IIR filter is an inverse dynamical controlfilter. The filter is a cascaded, inverse model of the engraving head 22and a filter with the desired frequency response. The inverse model ofthe head 22 was obtained by recursive least squares systemidentification with a white noise excitation of the engraving head 22.The desired frequency response is that of an eighth order real polefilter with all poles placed at 2-15 Khz, depending on desired engravingspeed. The resultant filter comprises a digital approximation of acontinuous control filter. The convolved value is then stored in outputbuffer OP at location OP INDEXG! (block 402).

The INDEXG (FIG. 14) is then incremented by one (block 404). At decisionblock 406, it is determined if INDEXG is equal to the length of outputbuffer OP, and if not, the method loops back to block 398 as shown.Otherwise, the method is complete and returns to block 214 (FIG. 6)where an output gain and offset routine is then performed by controller17.

Referring now to FIG. 15, the output gain and offset procedure begins byinputting a gain factor and an offset into controller 17. An INDEXH isequal to zero. Controller 17 sets a VALUEG equal to the value stored inbuffer OP at location OP INDEXH!. At block 414, VALUEH is determined orcalculated by multiplying VALUEG by the gain factor and then adding theoffset. In the present embodiment, the gain may vary between 2.0-30.0,and the offset is plus or minus 16,000.

INDEXH is incremented by one (block 418). At block 420, it is determinedif the INDEXH is equal to the length of output buffer OP. If it is not,the process loops back to block 412 as shown; otherwise, the process 410is complete and returns to block 216 (FIG. 6).

After the output gain and offset procedure is performed by controller17, the method proceeds to block 216 where output data for engraving theportion of the image data being processed is generated by controller 17.In this regard, FIG. 16 illustrates a method for outputting output datafrom output buffer OP. As shown in FIG. 16, the method starts at block450 where controller 17 sets an INDEXI equal to 0. At block 452, theVALUEI is loaded with the data stored at output buffer OP INDEXI!. Thisdata corresponds to output data which has been processed as describedherein.

At an appropriate time, controller 17 receives a timing pulse from anencoder 25 (FIG. 1) associated with drive motor 28 (block 454 in FIG.16). In response to the timing pulse, controller 17 outputs the dataVALUEI in digital form to D/A converter 19 (FIG. 1). The D/A converter19 converts the VALUEI data into an analog voltage which is amplified byan amplifier 21 (FIG. 1) and then used to energize engraving head 22 sothat engraving can be performed.

As mentioned earlier herein, once all data associated with an image tobe engraved has been engraved, then engraving is complete (block 220 inFIG. 6). Otherwise, the next column of input image data to be processedare input or obtained from, for example, external memory in accordancewith the image data procedure (block 222). In the embodiment beingdescribed, one suitable image data procedure is illustrated in FIG. 17which begins by copying image data located at buffer D2 into buffer D1(block 462) and copying image buffer data D3 into buffer D2 (block 464).The flag buffer F1 is cleared (block 466). At decision block 468,controller 17 determines if there is another column of image data to beprocessed. If there is, the method proceeds to load that next columndata into buffer D3 (block 470). If the answer at decision block 468 isno, then the controller 17 clears buffer D3 and the method returns toblock 202 in FIG. 6 for further processing. After all input columns ofdata are processed and the engraving is complete, a pattern 34 (FIG. 2)is engraved on the cylinder 14. The pattern 34 may have at least oneengraved area whose associated input data was modified to achieve adesired result, such as defining a horizontal line 36 (FIG. 2).

Advantageously, this procedure facilitates processing image data andlocating transitions between engraved and non-engraved areas forpurposes of modifying a location of one or more of the engraved areas.This, in turn, facilitates providing a pattern of engraved areas whichachieve desired characteristics, such as defined edges and lines.

FIGS. 18-32 illustrate another embodiment of the invention where acharacteristic or dimension of one or more areas of an image to beengraved is modified prior to engraving in order to enhance, modify orchange a characteristic of the engraved area to facilitate defining adesired engraved pattern. In this illustration, one or more of the areasto be engraved is modified to define or provide an elongated cell ortrench 100 (FIG. 3) to facilitate defining a substantially vertical edgeor line 35a (FIG. 3).

It should be appreciated that the procedures or methods shown in FIGS.18-32, which have some of the same procedures or methods as wasdescribed above relative to FIGS. 6-17. The procedures or methods whichare the same have the same block number, with the addition of a "'" markadded to the numbers used in FIGS. 18-32.

Referring now to FIG. 18, image data is loaded into three buffers D1,D2, and D3 (block 200'). One method for performing this load procedureis illustrated in FIG. 20 which is substantially the same as theprocedure described above relative to FIG. 8.

After the data buffers are set and/or loaded with image data for animage to be engraved, a vertical scan routine is performed (block 201')which is described in detail below. Then a horizontal scan routine isperformed (block 203').

Image data in the D2 buffer is copied into output buffer OP at block204' in accordance with the method shown in FIG. 23 and which issubstantially the same as the method and procedure described relative toFIG. 10 above. Upon completion of the copying routine, a DC gain orscale routine is performed (block 206') and then a combine routine isperformed at block 208'. The DC routine 206' is illustrated in FIG. 24which is substantially the same as the procedure and method describedwith the embodiment described above relative to FIG. 11.

The combine routine 208' is illustrated in FIG. 25 and comprises thesame method and procedure shown in FIG. 12A and described above. Themethod proceeds to a disable AC on vertical edges (block 209') and whichis described relative to FIGS. 26 and 27A-27D described below. Theprocedure continues to block 212' (FIG. 18) where controller 17 performsthe filter routine. It should be appreciated that the filter routine 15shown in FIG. 29 is substantially the same as the filtering procedureshown in FIG. 14 and described earlier herein.

As with the embodiment described earlier herein, this method proceeds toperform an output gain and offset routine (block 214'), and thereafter,engraving (block 216'). The output gain and offset routine 214' issubstantially the same as the output gain and offset routine describedabove relative to FIG. 15. Likewise, the engraving step 216' is shown inFIG. 30 and is substantially the same as the method shown in FIG. 16 anddescribed earlier herein.

It is determined at block 220' if all data associated with an image hasbeen processed. If it has, then the method is complete. If it has not,the method proceeds to block 222' where more image data routine isobtained and processed. It should be appreciated that the image datamethod is shown in FIG. 31 and is the same as that shown in FIG. 17described earlier herein. In the embodiment being described, theprocedure then loops back to block 201' as shown.

Referring now to FIG. 21, the vertical scan routine is shown. Thisprocedure begins by setting an INDEXN equal to zero (block 432'). Atdecision block 434', it is determined if the value stored at buffer D2location D2 INDEXN! is less than a predetermined threshold, which inthis embodiment is set at one. If it is, then the INDEXN is incrementedby one (block 438'). Thereafter, it is determined at block 440' whetherthe INDEXN is equal to a length of buffer D2. If it is not, then themethod loops back to decision block 434. If it is, then the method iscomplete and the method proceeds to block 203' (FIG. 18).

If the answer at decision block 434' in FIG. 21 is negative, then theINDEXN is incremented by one (block 436'). The method proceeds todecision block 442' where it is determined if a value stored a buffer D2location D2 INDEXN! is greater than a predetermined threshold, such as254 in the embodiment being described. If it is not, then the methodloops back to 434' as shown.

However, if the decision at decision block 442' is yes, then it isdetermined whether the data value stored at buffer D1 location D1INDEXN! or the value stored at data buffer D3 INDEXN! is less than apredetermined threshold (block 444'), such as one in this embodiment. Ifeither of them are less than the predetermined white threshold, then aflag in the flag buffer F1 is set at location F1 INDEXN!. This flagidentifies a vertical edge, such as edge 36a (FIG. 3), in the imagedata.

Thereafter, or if the decision at decision block 444' (FIG. 21) isnegative, then the method proceeds to increment the INDEXN by one (block446'). At decision block 449', it is determined if INDEXN is equal to alength of buffer D2. If it is, then the method is complete and itreturns to block 201' (FIG. 18). If it is not, however, then the routineloops back to decision block 442' (FIG. 21) as shown.

FIGS. 22A and 22B illustrate a scanning procedure utilized by controller17 for processing image data in order to locate horizontal areas, suchas a horizontal edge or line.

The method starts at block 256' by setting an INDEXP equal to zero. Atdecision block 257', if the value stored in data buffer D2 at D2 INDEXP!is less than a predetermined white threshold, then INDEXP is incrementedby one (block 258'). At block 260' it is determined if the INDEXP indexis equal to the length of the D2 buffer, and, if it is, then the methodis complete. If the INDEXP is not equal to the length of the D2 buffer,then the method loops back to decision block 257'. When the decision atblock 257' is negative, the method proceeds to block 262' where thewhite-to-black flag is set in flag buffer at F1 INDEXP! (block 262').Next, the INDEXP is incremented by one. A COUNTP is set equal to zero(block 264').

At decision block 268', it is determined if the value stored in databuffer D2 at D2 INDEXP! is greater than a predetermined black thresholdwhich is set at 254 in this embodiment. If it is, then INDEXP isincremented by one, and the COUNTP is incremented by one at block 270'.The method proceeds to block 266' where it is determined if the INDEXPis equal to the length of the D2 buffer. If it is, the method exits,otherwise, it loops back to block 268' as shown.

At block 272', a LENGTHP is set equal to the COUNTP and theblack-to-white flag is set in flag buffer at F1 INDEXP! (block 274).

The method proceeds to decision block 276' where it is determined if theLENGTHP is greater than a predetermined length, such as 12 samples. Ifit is not, the method proceeds to block 278' where the INDEXP is set tothe INDEXP minus the LENGTHP. At block 280', the flag in the flag bufferis set at F1 INDEXP!. This flag is a trench flat which identifies dataassociated with an area where it is desired to locate the modifiedengraved area, such as trench 100 in FIG. 3. At block 282', the INDEXPis incremented by one and the COUNTP is decremented by one as shown.

At decision block 284', it is determined whether COUNTP is zero. If itis, the method loops back to decision block 257' as shown. If it is not,the method loops back to block 280'.

If the decision at decision block 276' is yes, then the method proceedsto block 286' (FIG. 22B) where the INDEXP is set at the INDEXP minus theLENGTHP.

At block 288', a flag in flag buffer is set at FI INDEXP!. This flag isa trench flag which identifies data associated with an area where it isdesired to locate the modified engraved area, such as trench 100 in FIG.3. The INDEXP is incremented by one (block 290') and the COUNTP isdecremented by one.

It is then determined at decision block 292' whether the COUNTP plus apredetermined value, such as 9 samples, is greater than the LENGTHP. Ifit is, then the routine loops back to block 288'; otherwise, it proceedsto decision block 294' where it is determined if the COUNTP is greaterthan another predetermined value, such as 8 samples. If the COUNTP isnot greater than the predetermined value, then the INDEXP is incrementedby one and the COUNTP is decremented by one at block 296'. The methodthen loops back to decision block 294' as shown. If the decision atdecision block 294' is no, then the flag in the flag buffer is set at F1INDEXP! (block 298'). This flag is a trench flag which identifies dataassociated with an area where it is desired to locate the modifiedengraved area, such as trench 100 in FIG. 3.

At block 300', the INDEXP is incremented by one and the COUNTP isdecremented by one as shown. The method proceeds to decision block 302'where it is determined if the COUNTP is greater than zero. If the COUNTPis greater than zero, then the method loops back to block 298'. If theCOUNTP is not greater than zero, then the method proceeds to decisionblock 304' as shown. At decision block 304', it is determined if theINDEXP is equal to the length of the D2 buffer. If it is, then theprocedure is complete. If it is not, the routine loops back to decisionblock 257' (FIG. 22A) as shown. It should be appreciated that after thehorizontal edge scan is performed by controller 17, the horizontal edgesor transition in the image data are flagged or identified for furtherprocessing by the disable AC routine (FIGS. 26 and 27A-27D).

At this point, controller 17 processes the data in accordance with thecopy image data routine (block 204' in FIG. 18) gain or scale routine(block 206') and then the combine routine (block 208') all of which arethe same as described above relative to the first embodiment.

Next, controller 17 performs the disable AC routine (block 209' in FIG.18) which is illustrated in detail in FIGS. 26 and 27A-27D which willnow be described. This method or procedure begins at block 554' (FIG.26) by setting INDEXQ equal to zero. At decision block 556', it isdetermined if the trench flag in flag buffer at location F1 INDEXQ! isset. If it is not, the INDEXQ is incremented by one (block 558'). It isthen determined (block 560') if the INDEXQ is greater than the length ofthe flag buffer F1. If it is, then the routine is complete and returnsback to block 512' (FIG. 18). Otherwise, it returns to decision block556' as shown.

If the decision at decision block 556' is yes, then a COUNTQ is setequal to one and the INDEXQ is incremented by one (block 562'). It isthen determined at decision block 564' if the valve in the flag bufferat location FI INDEXQ! has the trench set. If it is set, INDEXQ isincremented by one and the COUNTQ is incremented by one (block 566'). Itis then determined if the INDEXQ is greater than a length of the flagbuffer F1 (block 568'). If it is, then the routine is complete,otherwise it loops back to decision block 564' as shown.

If the decision at decision block 564' is no, then it is determined(block 570') if the COUNTQ is greater than a preset value, such as twoin the embodiment being described. If it is, then an adjust regionroutine described below is performed by controller 17. If the decisionat decision block 570' is negative or after block 572', the method loopsback to decision block 556' as illustrated.

It should be appreciated that the disable AC routine facilitateslocating all flagged data which represents areas in a final engravedpattern where one or more trenches, such a trench 100 in FIG. 3, shouldbe placed. Once the flagged data is located, the length thereof isdetermined and stored in COUNTQ. COUNTQ is then used by controller 17 inan adjust region routine which facilitates disabling a portion of thedata, so that the trench can be engraved.

The adjust region procedure (block 572' in FIG. 26) will now bedescribed in detail relative to FIGS. 27A-27D.

Referring now to FIG. 27A, the adjust method starts by first adjustingthe start region (block 574'), adjusting a center region (block 576'),and then adjusting an end region (block 578'). The adjust region routinedefines a procedure for adjusting output data associated with a trencharea in order to smooth the transition into and out of the trench.

FIG. 27B illustrates a procedure for adjusting the start region of thetrench. The process begins at block 580' by setting an INDEXR variableequal to INDEXQ-COUNTQ (FIG. 26). Also, an INDEXS variable is set equalto INDEXR multiplied by 8. INDEXR is used to locate positions in flagbuffer F1 which comprises four samples per engraved area in theembodiment being described. INDEXS is used to locate positions in theoutput buffer OP which is sampled at 32 samples per engraved area. Thismakes it necessary to multiply the flag buffer position by 8 in order tofind the position in the output buffer OP corresponding to the positionin the flag buffer.

At decision block 582' it is determined if a white-to-black flag in flagbuffer at location FI INDEXR! was set at block 262' in FIG. 22. This isdone to determine if the trench is starting in a non-engraved orengraved area. If it is, then output buffer OP is filled with a VALUEQfrom controller 17 beginning at OP INDEXS-X!, where X is a predeterminedlength which is set at 8 samples in this embodiment. The output bufferOP is filled through the OP INDEXS! location with the VALUEQ. The VALUEQis determined to be 50% of the magnitude of the value listed in the sinewave table (block 344' in FIG. 25).

It should be appreciated that the method generally overwrites dataimmediately preceding the trench data so that engraving head 22 respondsas desired. In order to transition smoothly into the trench, the dataimmediately preceding the trench is overwritten with transition date. Inthis regard, FIG. 32 illustrates a combined drive signal 55 having an ACportion 55a and a DC portion 55b which corresponds to the trench to beengraved.

The transition data corresponds to portion 55c which is where the ACportion 55A begins to be disabled. In the embodiment being described,VALUEQ1 is set at 50% of the AC amplitude.

If the decision at block 582' (FIG. 27B) is no, then the same area isfilled (block 584') with a VALUEQ2 which is 65% of the AC magnitude(block 344' in FIG. 25).

The start region adjustment method is now complete and the methodreturns to FIG. 27A, block 576'.

Next, the center region of data corresponding to the trench by settingan INDEXT equal to INDEXR multiplied by 8 (block 588') for reasonsdescribed above. A COUNTT is set equal to COUNTQ multiplied by 8.

At block 594', the output buffer OP is filled starting at position OPINDEXT! through OP INDEXT+COUNTT! with data value, VALUET. In thisembodiment, the VALUE T is set at 74% of the AC magnitude (FIG. 25,block 344'). This causes the trench corresponding to portion 55b in FIG.32 to be generated.

This method of modifying the combined signal is now complete and theprocess proceeds to FIG. 27A, block 578'. At this point, an adjust endregion procedure is performed as will now be described relative to FIG.27D.

First, a new INDEXV is set equal to INDEXQ multiplied by 8 (block 610')in FIG. 27D.

At block 610', the flag buffer is checked to see if a flag was set whichwould indicate that there was a black-to-white edge at F1 INDEXQ!. Ifyes, then the output buffer is filled at output buffer locations OPINDEXV! through OP INDEXV+Y! (where Y is a predetermined number ofsamples, such as 8), with a VALUEV1 which is set at 50% of the magnitudeof the AC waveform (block 614').

If the decision at block 610' is no, then the same area of output bufferOP is filled with VALUEV2, which is set to the negative of 15% of themagnitude of the AC amplitude. It should be appreciated that thepercentages used in FIGS. 27B, 27C and 27D could be set higher or loweras desired.

After blocks 612' or 614', the method of adjusting is complete and theprocess returns to block 278' (FIG. 27A) and then to block 212' (FIG.18). At this point the combined data, as it may have been modified asdescribed herein, is ready to be filtered by controller 17 in accordancewith the procedure described in FIG. 28 which is substantially the sameas the procedure described earlier relative to FIG. 14.

The output gain and offset routine (block 214') is performed next. Thisroutine is shown in FIG. 29 and is substantially the same as the routinedescribed earlier herein relative to FIG. 15.

The output data for at least a portion of the image to be engraved,including any portions thereof that were modified, is engraved (block216') in the same manner as described earlier herein relative to thefirst embodiment.

Controller 17 energizes digital-to-analog converter 19 in response tooutput data generated by output buffer OP in FIG. 30. The converter 19generates an analog signal, such as 48 in FIG. 5, which is amplified byamplifier 21, and this signal is used to energize engraving head 22.

At decision block 220' (FIG. 18), it is determined if all data for animage to be engraved has been engraved, and if it has, then engraving iscomplete. Otherwise, the method proceeds to block 222' where new imagedata is obtained in accordance with the image data routine illustratedin FIG. 31. This routine is substantially the same as the routine shownin FIG. 17 and described earlier herein.

Advantageously, this alternative embodiment permits the engraving of anenlarged area, cell, edge or trench which defines an edge or line in apattern by identifying transition areas and then generating a signalwhich will cause a vertical edge, such as the edge 36a in FIG. 3, to beengraved in order to define a sharp line, for example, in a printedimage when the engraved pattern is used in a printing process. Thisprocedure also facilitates manipulating engraving input data for animage to be engraved so that a dimension or characteristic of an area tobe engraved can be modified or changed in order to provide an engravedpattern having at least one area which is manipulated or modified asdesired.

A method of operation will now be described. The cylinder 14 isrotatably mounted between headstock 16 and tailstock 18 at the engravingstation 15. Controller 17 energizes drive motor 28 to rotatably drivecylinder 14k in the direction of arrow A (FIG. 2). The controller 17energizes drive motor 21 to drive carriage 24 towards end 14a ofcylinder 14. At this point, one or test cuts may be performed as desiredand then engraving can begin.

The image data associated with an image to be engraved is then processedcolumn by column in the manner described earlier herein. In theembodiment being described, engraving is performed by controller 17energizing drive motor 21 to drive carriage 24 as the engraving head 22and engraving device 23 is excited in response to the processed imagedata so as to affect engraving of one or more engraved areas or cellswhich make up a pattern, such as the pattern 34 shown in FIG. 2.

After engraving is complete, controller 17 can energize drive motors 46and 48 to retract headstock 16 and tailstock 18, respectively, so thatcylinder 14 can be removed.

Cylinder 14 may then be put in a printing press so that printing on aworkpiece can be performed.

Advantageously, this invention facilitates manipulating image data sothat areas engraved in response to that data have desiredcharacteristics. For example, this invention facilitates defining sharpor generally non-jagged lines or edges in the pattern engraved. This, inturn, facilitates engraving characters or images having fine detail.

The method and apparatus described herein also facilitates easyidentification of transition areas and manipulation of image data.

Further, the method and apparatus provides means for identifying an areaof image data to be modified and modifying or changing that data inaccordance with a predetermined shaping waveform which furtherfacilitates achieving the advantages described herein.

The filtering means and method described herein facilitate compensatingthe output data in order to maximize the performance of the engravinghead 22. Also, the filtering means and method described hereinfacilitates filtering a signal comprised of a steady state and videocomponents, regardless of whether one or more or all of those componentshave been modified in accordance with the procedure described herein.

It has been found that the method and apparatus described herein isprogrammable and easily adjustable to provide an engraving system andapparatus which is easily adaptable.

While the method herein described, and the form of apparatus forcarrying this method into effect, constitute preferred embodiments ofthis invention, it is to be understood that the invention is not limitedto this precise method and form of apparatus, and that changes may bemade in either without departing from the scope of the invention, whichis defined in the appended claims.

What is claimed is:
 1. A method for engraving a plurality of cells whichdefine a pattern defining at least one edge on a surface of a cylinder,comprising the steps of:providing a bed; providing a headstock and atailstock for rotatably supporting a cylinder on the bed; providing anengraving device mounted on said bed for engraving a surface of thecylinder; providing a controller for controlling operation of theengraving device; and providing a signal generator located in saidcontroller for generating an edge signal corresponding to an edge cellsituated in said pattern; said engraving device engraving said edge cellat a predetermined location in the pattern to facilitate defining saidat least one edge in response to said edge signal.
 2. The method asrecited in claim 1, further comprising:selecting said edge signal from aplurality of edge signals.
 3. The method as recited in claim 2, furthercomprising:situating said plurality of edge signals in a table.
 4. Themethod as recited in claim 1, further comprising:using said edge signalto modify an image signal corresponding to an image to be engraved toprovide a drive signal for energizing the engraving head.
 5. The methodas recited in claim 1, further comprising:generating an edge signalcorresponding to an edge cell which is compressed.
 6. The method asrecited in claim 1, further comprising:generating an edge signalcorresponding to an edge cell which defines a trench.
 7. The method asrecited in claim 1, further comprising:generating a plurality edgesignals which define a plurality of edge cells and which define said atleast one line.
 8. The method as recited in claim 1, further comprisingthe step of:locating a plurality of edge cells which define said atleast one edge in said image.
 9. The method as recited in claim 8,further comprising the step of:tabulating a set of data corresponding toat least a portion of an image to be engraved; locating said at leastone edge using said set of data.
 10. The method as recited in claim 1,further comprising the step of:shifting a locating of said edge cell tofacilitate defining said at least one edge.
 11. The method as recited inclaim 1, said method further comprising the steps of:providing a set ofdata corresponding to an image to be engraved; processing said set ofdata such that said pattern comprises at least one compressed area. 12.The method as recited in claim 1, said method further comprising thesteps of:providing a set of data corresponding to an image to beengraved; processing said set of data such that said pattern comprisesat least one enlarged area.
 13. The method as recited in claim 12,wherein said at least one enlarged area comprises at least onecontinuous trench.
 14. The method as recited in claim 12, furthercomprising the step of:providing a set of data corresponding to saidimage; processing said set of data such that said comprises at least oneenlarged area defining a vertical pattern.
 15. The method as recited inclaim 1, further comprising the step of:providing a set of datacorresponding to an image to be engraved; evaluating said set of data tolocate edge data corresponding to at least one edge; generating a shiftsignal in response to said edge data.
 16. The method as recited in claim15, further comprising:selecting said shift signal from a plurality ofshift signals stored in a processor.
 17. The method as recited in claim1 wherein said pattern is adjacent said at least one edge, said methodfurther comprising the step of:processing a signal corresponding to saidpattern such that said pattern defines at least a portion of said atleast one edge.
 18. An engraver for engraving a pattern having at leastone edge, comprising:a bed; a headstock and a tailstock for rotatablysupporting a cylinder on the bed; an engraving device mounted on saidbed for engraving a surface of the cylinder; a controller forcontrolling operation of the engraver and coupled to said engravingdevice; and a signal generator located in said controller for receivingimage data corresponding to an engraved area having a predeterminedcharacteristic, for processing said image data in order to change saidpredetermined characteristic to facilitate defining said at least oneedge, and for generating an engraving signal in response thereto forenergizing said engraving device.
 19. The engraver as recited in claim18 wherein said controller comprises:a locator for locating said atleast one edge.
 20. The engraver as recited in claim 18, furthercomprising:a tabulator for tabulating a table of data situated in saidprocessor and corresponding to at least a portion of the image to beengraved; a locator for locating said at least one edge using said setof data.
 21. The engraver as recited in claim 18 wherein said signalgenerator causes an engraving location of said area to be shifted tofacilitate defining said at least one edge.
 22. The engraver as recitedin claim 18 wherein said signal generator causes said area to be reducedin order to change said predetermined characteristic.
 23. The engraveras recited in claim 18 wherein said signal generator generates an edgesignal for engraving at least one enlarged area.
 24. The engraver asrecited in claim 23 wherein said at least one enlarged area comprises atleast one continuous trench.
 25. The engraver as recited in claim 18wherein said signal generator generates an edge signal for engraving atleast one enlarged area defining a generally vertical edge.
 26. Theengraver as recited in claim 18 wherein said signal generator comprisesa shift signal generator for generating a shift signal for modifyingsaid engrave signal.
 27. The engraver as recited in claim 18 whereinsaid controller comprises a plurality of shift signals stored therein,said shift signal generator selecting said shift signal from a pluralityof shift signals stored in said controller.